p1177 Search simple questions

　　It's really simple, just search directly as required. Although I don't know whether the horizontal row represents the work or the vertical column, but the search is still the same.

　　

 1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<cstring>
 5 #include<cmath>
 6 using namespace std;
 7 int i,f,n,o[30][30],ans=200000;
 8 bool flag[30];
 9 void dfs(int sum,int now)
10 {
11     if(sum>=ans) return ;
12     if(now==n)
13     {
14         ans=sum;
15         return ;
16     }
17     now++;
18     for(int j=1;j<=n;j++)
19     {
20         if(flag[j]==0)
21         {
22             flag[j]=1;
23             dfs(sum+o[j][now],now);
24             flag[j]=0;
25         }
26     }
27     return;
28 }
29 int main()
30 {
31 ios::sync_with_stdio(false);    
32     cin>>n;
33     for(i=1;i<=n;i++)
34         for(f=1;f<=n;f++)
35             cin>>o[i][f];
36     for(i=1;i<=n;i++)
37     {
38         flag[i]=1;
39         dfs(o[i][1],1);
40         flag[i]=0;
41     }
42     cout<<ans;
43 }

p1177

　　Then the reason for the delay is actually that I am used to making the loop variable global. In this question, the variables inside dfs cannot be changed by their own lower layers. Then there are only a few special cases.

　　There is also a small fear: if the person who gave the question gave the same data for all working hours, wouldn’t it explode, even if (sum>=ans)return was optimized; the complexity would still be n to the nth power, it’s simply .